A wind turbine generator is a device for generating power by a power generator driven by rotation of a rotor head provided with a turbine blade upon receipt a wind force and by increasing a speed of this rotation by an accelerator or the like. The rotor head is mounted on an end portion of a nacelle installed on a tower for a wind turbine, capable of yaw turning, and is supported rotatably around a rotation axis in a substantially horizontal lateral direction.
A nacelle cover covering the nacelle of a wind turbine generator is configured by connecting a plurality of panels, and a connection portion structure of this panel needs to be constructed such that penetration of rainwater from the outside of the nacelle cover into the inside can be prevented.
The connection portion of the panels is generally joined by a bolt, but if the nacelle cover is subjected to an external force due to wind pressure, snow fall or the like, the panel connection portion joined by this bolt becomes the weakest part in terms of strength. Therefore, the panel connection portion needs to have a structure in which a high material distortion does not occur.
General structures for a connection portion of wall surface panels include the one illustrated in Patent Document 1, for example.